Segment Information - Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net investment income	$ 2,305	$ 2,177	$ 2,313
Operating Segments | P&C Commercial Lines
Segment Reporting Information [Line Items]
Net investment income	1,532	1,415	1,502
Operating Segments | P&C Personal Lines
Segment Reporting Information [Line Items]
Net investment income	171	140	157
Operating Segments | Property & Casualty Other Operations
Segment Reporting Information [Line Items]
Net investment income	69	63	75
Operating Segments | Group Benefits [Member]
Segment Reporting Information [Line Items]
Net investment income	469	524	550
Operating Segments | Hartford Funds
Segment Reporting Information [Line Items]
Net investment income	17	9	5
Corporate
Segment Reporting Information [Line Items]
Net investment income	$ 47	$ 26	$ 24